There's no getting around it: if you want to get good at playing the ukulele or any other instrument, you'll need to practice. Fortunately, the Internet is awash in free uke lessons, like this one from Ukulele Live, which make the task not only easy but fun. This clip, in particular, demonstrates how to perform old-school jazzy introductions and outros on the uke.

The idea is based around a 4 chord progression: I, VIm, IV, V7. This is the progression that is used in "Surf" and many other songs. By themselves those chords sound pretty "Surf-ish", so they need to be jazzed out. To jazz things up, you will use substitution chords.

Substitution chords are chords that fit right over the top of the normal chord and add a different sound without disturbing the tonality of the main chord. For example, C6 can fit over C, Adim can fit over Am, Dm7 fits over F, and G7 stays the same. Any combination of chords that sound good will work, so experiment to find your favorite sounds.